To make the perfect marinara sauce, don't simmer the sauce for too long. This sauce relies on fresh tomatoes, and simmering them for too long can alter their initial flavor.

To maintain the tomatoes' integrity, don't cook the sauce for more than 20 minutes, or else they break down and lose moisture, resulting in a thicker texture and different flavor.

Since marinara's flavor comes from a bright, acidic tomato taste and is supposed to be thinner, simmering the sauce for hours will change it into something completely different.